1. Field of the Invention
The present invention relates to a power feeding device and a wireless power feeding system including the power feeding device.
2. Description of the Related Art
Various electronic appliances have spread and a variety of products is shipped to the market. In recent years, the spread of portable electronic appliances such as cellular phones and digital video cameras is apparent. In addition, electric mobile units powered by electricity, such as electric cars, are going on the market.
A cellular phone, a digital video camera, or an electric mobile unit has a built-in battery serving as a storage battery. Currently, the battery is made, in most cases, in direct contact with a household AC power source, which serves as a power feeding unit, to be charged. In addition, a unit without a battery or a unit which does not use power stored in a battery is currently powered by direct feeding electricity to the unit from a household AC power source through wiring or the like.
On the other hand, research and development of methods of wirelessly charging batteries or feeding electricity to loads is advancing. Typical examples include the electromagnetic coupling method (also called the electromagnetic induction method), the radio wave method (also called the micro wave method), and the resonance method. Some of electronic appliances using the electromagnetic coupling method, including small home electrical appliances, have already spread.
Wireless power feeding systems using the resonance method are being developed in order to increase efficiency of power transmission (power transmission efficiency) as described in Patent Document 1 or 2.